Tried to make lined shading go with the contours at first, but it didn’t work on this object. Generally a little tricky to do as each line must gradually change contour.
![Vase with contours](https://devyse.co.uk/wp-content/uploads/2021/01/20210124b-1024x957.jpg)
Then a drawing of a pear:
![A pear](https://devyse.co.uk/wp-content/uploads/2021/01/20210124a-1024x600.jpg)
An attempt to shade it using only black and mid-grey:
![A shaded pear](https://devyse.co.uk/wp-content/uploads/2021/01/20210124c.jpg)
This wasn’t a success because it’s difficult to give a sense of form with only two shades. Probably works okay with angular forms, but not so much organic forms. Need to introduce an extra shade.